This application claims the benefit of Korean Patent Application No. 2003-96292, filed on Dec. 24, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a spotting device for manufacturing a DNA microarray and a spotting method using the same. More particularly, the present invention relates to a spotting device for dropping and immobilizing a solution of biomolecules, for example, nucleic acids such as probe DNA, mRNA, and peptide nucleic acid (PNA), and proteins on a DNA microarray surface to manufacture a DNA microarray and a spotting method using the same.
2. Description of the Related Art
With progress on the human genome project, a demand for a method to rapidly provide an enormous amount of genetic information with regard to the diagnosis, treatment, and prevention of hereditary diseases has greatly increased. Though a method of Sanger which had been used to analyze a base sequence until that time was steadily progressed by the development of a polymerase chain reaction (PCR) replicating DNA and automation thereof, it could not analyze a large number of genes since an analyzing process was complicated, time consuming, expensive, and high degree of skills were required. Thus, a new system for analyzing a base sequence has been continuously required. According to the needs of the times, there was progress in a manufacturing of a DNA microarray and a technology using the same for last several years.
The “DNA microarray” generally refers to attaching oligonucleotide probes, of which a base sequence is known, having from the minimum several bases to the maximum hundreds of bases to a surface of a solid, such as silicone, surface modified glass, polypropylene, and activated polyacrylamide, at hundreds or one hundred thousands of predetermined positions to microarray. When bonding a target DNA fragment intended to analyze to the DNA microarray, various hybridizations according to a compensatory level between base sequence of the probe attached to the DNA microarray and base sequence of the target DNA fragment occur and are observed and analyzed through an optical method or a radiochemical method to discover the base sequence of the target DNA (sequencing by hybridization; SBH).
A DNA chip manufactured using the DNA microarray can achieve miniaturation of a DNA analysis system, perform a gene analysis using only an ultra trace volume of a sample and examine simultaneously base sequences at various positions on the target DNA. Accordingly, the DNA chip is inexpensive and can rapidly provide genetic information. Also, the DNA chip can simultaneously analyze an enormous amount of genetic information rapidly and clarify the relations between genes, and thus, will be applied to numerous fields, such as the diagnosis of hereditary diseases and cancers, search of a mutant, detection of pathogenic bacteria and fungi, analysis of gene expression, and drug development. Also, the DNA chip can be used in biotech to bring about development. For example, it can be used as a sensor of microorganisms and environmental pollution to find a gene for a material to neutralize poison and gene recombination technology is applied thereto so as to mass produce the material which neutralizes poison or produces crops for medicines and low fat meat.
The DNA microarrays may be divided into oligo chips and cDNA chips according to a type of a probe used and may be divided into photolithography chips, spotting chips using a pin, and spotting chips using inkjet according to a manufacturing method. FIGS. 1 and 2 illustrate conventional spotting methods using a pin and inkjet, respectively, for manufacturing a DNA microarray. In the methods, a solution of biomolecules, for example, nucleic acids, such as probe DNA, mRNA, PNA, and proteins, are dropped and immobilized on a DNA microarray surface. All biomolecules used in the methods are in liquid state.
Regarding conventional spotting devices for manufacturing a DNA microarray and spotting methods using the same, in the case of using a pin, since the pin is used to spot a biomolecule solution which is then washed, and then it is used to spot another biomolecule solution, 99% or more of a biomolecule solution is discarded without being used. Also, the sizes of spots are not uniform, the pin is occasionally clogged, life time of the pin is not long, the concentration of the biomolecule solution is varied according to spotting time, and long time is required for spotting the biomolecule solution. In the case of using inkjet, a bubble jet method momentarily requires ultrahigh heat, and thus, a part of the biomolecules which are sensitive to heat may be affected by the heat. Also, a nozzle is occasionally clogged.